This invention relates to an automatic setting method of a receiving channel of a receiver wherein a television (TV) broadcast through ground waves and a CATV (cable television) broadcast through wire search channels according to each channel plan to store in a memory device.
Heretofore, since channel plans for TV broadcast through ground waves and CATV broadcasts are different in both transmission passages (in the case of ground waves the broadcast is space, while CATV uses an exclusive cable), each channel in the same frequency zone was allotted to overlap. Further, with CATV broadcasts, many channels are allotted to frequency zones which are not used for ground wave broadcasts.
FIG. 5 is a block drawing which shows a setting method of receiving channels of a traditional receiver. In the Figure, numeral 1 is a television antenna for receiving a television broadcast wave of a ground wave, 2 is a distributor, 3 is a cable connecting terminal and 4 is a receiver input terminal. The numeral 7 is a signal processing portion where the frequency conversion is conducted against the received signal, 8 is a channel selecting portion where a desired signal of the channel frequency from the received signal is selected, and 10 is an intermediate frequency amplification portion which amplifies a signal converted into the intermediate frequency zone in the signal processing portion 7.
The numeral 11 is a slide switch for setting a receiving mode of the receiver itself to either the television broadcast through ground wave or CATV. When this is set in a mode to receive the ground wave TV, a slide switch is moved to the upper side, while if set to a CATV receiving mode, said switch is moved to the lower side.
Thus, in the receiving channel setting method of the traditional receiver, when the channel of TV broadcast of the ground wave is set, a user of the receiver operates the switch 11 in advance, thereby setting the receiving mode of the receiver to the receiving mode of the TV broadcast of the ground wave. As a result, in the channel selection portion 8 of the receiver, the channel is searched to be set to store according to the channel plan of the TV broadcast of the ground wave previously memorized. Further, when receiving CATV broadcasts, the switch 11 is operated to set the receiving mode of the receiver to the receiving mode of the CATV broadcast, whereby the channel is searched to be memorized according to the channel plan of the CATV broadcast previously memorized.
Since the automatic setting method of the receiving channel in the traditional receiver is composed as above, when the user intends to set the above channel, it is necessary to select the TV broadcast of the ground wave or the CATV broadcast beforehand. It is therefore not easy to operate for a user unaccustomed to the operation of the receiver.
This invention is performed to solve such problems, and its object is to provide an automatic receiving channel setting method of a receiver wherein the receiver searches a part of the receiving channel automatically thereby judging whether it is TV broadcast of the ground wave or CATV, and remaining channel searches and memorizes according to said channel plan.